Baked Mashed Potato Frittata (6 servings) 8 large eggs 3 cups mashed potatoes 2 bell peppers - finely chopped 1 cup onion - finely chopped 1 and 1/2 cups mushrooms - sliced 1/2 cup cheese (Parmesan is best; Cheddar works) - grated 4 Tablespoons vegetable or canola oil Preheat oven to 325 degrees F. In a large oven-safe skillet at medium-low heat, saute the peppers, onion and mushrooms until the vegetables are tender - stirring often. In a large bowl, whisk together the eggs, potatoes and cheese. Stir in vegetables from the skillet into this mixture.. In the same skillet (no need to clean first), heat 2 more tablespoons of oil(raise temperature to about medium). Pour the egg mixture into the skillet. Cook on stove top only until bottom is set. Carefully, transfer the skillet to the preheated oven. Bake for about 20 minutes until the frittata is fully set. To serve, cut in wedges. A frittata-style omelet with mashed potatoes, mushrooms, onions, peppers and Parmesan cheese. This is our favorite way to use leftover mashed potatoes. Mr Breakfast would like to thank PromQueen for this recipe. Recipe number 1146. Submitted 11/23/2003.